#define  _CRT_SECURE_NO_WARNINGS 1	
#include<stdio.h>
char* my_strcat(char* str1, const char* str2)
{
	char* ret = str1;
	while (*str1 != 0)
	{
		str1++;
	}
	while (*str1 = *str2)
	{
		str1++; 
		str2++;
	}
	return ret;
}
int main()
{
	char arr1[20] = { "abc" };
	char arr2[] = { "def" };
	printf("%s", my_strcat(arr1, arr2));
	return 0;
}
